The word nostalgia — combining the Greek nostos, “returning home,” and algia, “pain” — was coined by 19-year-old Swiss medical student Johannes Hofer in his 1688 medical dissertation. In a not highly scientific work (it was, after all, 1688) Hofer defined nostalgia as a disease resulting in “the pain a sick person feels because he is not in his native land, or fears never to see it again.” The symptoms of what we would now consider an acute psychological illness included lack of appetite, pallor, muscle weakness, general sadness and hopelessness.
In short order, the disease of nostalgia was prevalent among Swiss mercenaries, rustic boys overcome by homesickness after being sent throughout Europe to ply their armed trade. The nostalgia disease quickly went a 17th-century version of viral; Swiss, then German, French, English and American physicians latched on to it to explain a host of diseases of unknown origin. For more than a century, nostalgia was observed through a primarily medical lens.
By the mid-19th century, as medicine grew more sophisticated, the word nostalgia began trending toward its current usage: “A sentimental longing or wistful affection for a period in the past, typically for a period or place with happy personal associations,” as the Oxford English Dictionary has it.